The energy cost associated with the operation of a hot tub can raise energy bills an alarming amount For instance, it is common for a hot tub within a 60 degree F. environment to require 40,000 BTU's per day to maintain its water at a temperature of 100 degrees F. If electricity is used to supply the heat, the cost would be over $26/month (based on a rate of 10 cents per kilowatt hour and 1 kilowatt=3400 BTUs). In winter, hot tub electrical heating costs can exceed $100/month!
Gas is typically is many times cheaper than electricity for equivalent heating. Heating a hot tub needing 40,000 BTUs/day with gas would cost only $9/month (assuming a rate of 0.6 cents/cubic foot, 1 cubic foot =1030 BTUs and 75% efficiency). Thus in an effort to curb hot tub heating expenses there have been developed hot tub heaters which use gas to heat the water. However, conventional gas fired hot tub heaters present their own problems. For instance, they are very expensive at a typical retail price exceeding $1000. Also, they require their own gas line and a substantial amount of room. Quite simply, the complexity and expense of conventional gas or oil fired hot tub heaters prevent their use in most situations.
The present invention discloses a hot tub heater which utilizes a typical domestic hot water heater. The invention eliminates the need for installation of a separate and redundant gas fired device with the associated problems of space requirements, maintenance, fuel supply, safety, etc.